This invention relates to electronic article surveillance ("EAS") systems and, in particular, to EAS systems having a central control station and multiple local stations.
In recently developed EAS systems, a central control station has been used to control the operation of several local stations. Each local station has associated with it transmitter antenna assemblies and receiver antenna assemblies (also referred to as "detection units") which supply signals to and receive signals from associated interrogation zones.
The central control station includes equipment for developing drive signals for driving the transmitter antenna assemblies of the different local stations. It also includes equipment for interfacing with and processing the signals received from the receiver antenna assemblies of the different local stations. The latter processing includes processing the received signals to make EAS tag determinations and establish alarm conditions.
In the EAS systems developed to date, a central control station can only control local stations having the same personality. The personality of a local station is dictated by the physical structure and/or functions performed by the station and may include the following: the physical configuration of the associated transmitter and receiver antenna assemblies; the communication method or protocol used with the local station; the gain adjustment, tag detection parameter adjustment and receiver antenna phasing, all made based on noise, used with the local station; the alarming control used with the local station; and the accessory equipment control (e.g., EAS tag deactivator control, user management interface control) used with the local station.
The different personalities of local stations in use to date have arisen as a result of the need for EAS systems to satisfy different markets or applications. Examples of local stations having different personalities are those adapted for underfloor, overhead, entrance, exit and point-of-sale applications, respectively. In each of these types of stations, different associated transmitter and receiver antenna assemblies are used, which accounts, in part, for the differences in personality. These stations may also require different communication protocols, different receiver gains, different tag detection parameters, as well as different receiver antenna phasing, all of which account for other differences in personality.
As above-mentioned, central control stations in use today can only accommodate local stations having the same personality. This means that in a location with different personality local stations, multiple central control stations must be used. This adds to the expense and complexity of the EAS system.
It is, therefore, an object of the present invention to provide an improved EAS system.
It is a further object of the present invention to provide an EAS system in which different personality local stations can be used in a less complex and cost effective manner.